Develop Reference

Scaling an ImageView when the soft keyboard opens

I'm creating a tabbed activity. As long as the first tab is selected, the soft keyboard should be visible. I achieved that by adding this line to my manifest file in the activity tag:
android:windowSoftInputMode="stateVisible|adjustResize"
As the keyboard opens, the space for the layout shrinks. The most space is occupated by an ImageView. I want it to shrink with the layout size to allow the other 2 views (which should remain the same size) to fit on the screen. However, although the soft input mode is set to adjustResize, the ImageView keeps its size after the keyboard opens. Here's a comparison of the current layout and the one I want to achieve (the ImageView is the red rectangle):
comparison
My fragment's layout code:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout android:layout_width="match_parent"
android:layout_height="wrap_content"
xmlns:tools="http://schemas.android.com/tools"
tools:context=".DataInputFragment"
android:orientation="vertical"
xmlns:android="http://schemas.android.com/apk/res/android">
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:scaleType="fitStart"
android:src="#drawable/image"/>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:orientation="vertical">
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="#string/input_label_text"/>
<namespace.InputEditText
android:id="#+id/input_edit_text"
android:layout_width="match_parent"
android:layout_height="wrap_content"
<requestFocus/>
</namespace.InputEditText>
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="#string/submit"
</LinearLayout>
</RelativeLayout>
My activity:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/main_content"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:fitsSystemWindows="true"
android:orientation="vertical"
tools:context=".MainActivity">
<android.support.design.widget.TabLayout
android:id="#+id/tabs"
android:layout_width="match_parent"
android:layout_height="wrap_content"
style="#style/TabLayout">
<android.support.design.widget.TabItem
android:id="#+id/tabItem"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/tab_text_1" />
<android.support.design.widget.TabItem
android:id="#+id/tabItem2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/tab_text_2" />
</android.support.design.widget.TabLayout>
<android.support.v4.view.ViewPager
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="#string/appbar_scrolling_view_behavior" />
</LinearLayout>
How to force the ImageView to resize according to the screen size to make all of the views fit on the screen?
[EDIT]: My attempt to create a ConstraintLayout, which didn't solve the problem (the ImageView still keeps its original size):
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
tools:context=".DataInputFragment">
<ImageView
android:id="#+id/img"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:scaleType="fitStart"
android:src="#drawable/image"
android:adjustViewBounds="true"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="#+id/input_label"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="#string/input_label_text"
app:layout_constraintTop_toBottomOf="#id/img"/>
<namespace.InputEditText
android:id="#+id/input_edit_text"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_constraintTop_toBottomOf="#id/input_label">
<requestFocus />
</namespace.InputEditText>
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="#string/submit"
app:layout_constraintTop_toBottomOf="#id/input_edit_text"/>
</android.support.constraint.ConstraintLayout>

I've created an Android Project from scratch on Android Studio 4.0, using the "Tabbed Activity" template and uploaded it to GitHub.
I've had no issues with the resize taking place when the activity is resized.
What Did I change?
In the manifest.xml I added android:windowSoftInputMode="adjustResize"
I modified the default layout for the fragment in the tab to include an ImageView (called imageToShrink) and an EditText (called editLayout).
I left the existing TextView untouched, except that since it's at the top, I made it the HEAD of the vertical Chain, and gave it a 0.0 BIAS to be aligned at the top, rather at the center.
When you tap on the cyan EditText at the bottom, the keyboard pops (I made it number only so it's even taller) and you can see how the image is re-drawn after its new size is recomputed.
This is how it looks when it opens: (beautiful color palette!)
And this is how it looks when I tap the "edit field" to pop the keyboard:

your ImageView should not have wrap_content attributes, because it will always have constant size and wont be able to resize automatically. I would suggest using ConstraintLayout and use app:layout_constraintDimensionRatio. Other option is use LinearLayout weight (not recommending).
Ant third option is to detect when keyboard is visible, when not with ViewTreeObserver.OnGlobalLayoutListener and do stuff programmaticaly.
Try this:
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".DataInputFragment">
<ImageView
android:id="#+id/img"
android:layout_width="match_parent"
android:layout_height="0dp"
android:adjustViewBounds="true"
android:scaleType="fitStart"
android:src="#drawable/image"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintDimensionRatio="3:1"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.0" />
<TextView
android:id="#+id/input_label"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="#string/input_label_text"
app:layout_constraintTop_toBottomOf="#id/img" />
<EditText
android:id="#+id/input_edit_text"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_constraintTop_toBottomOf="#id/input_label">
<requestFocus />
</EditText>
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="#string/submit"
app:layout_constraintTop_toBottomOf="#id/input_edit_text" />
</android.support.constraint.ConstraintLayout>

How to Control Visibility of items in a Linear Layout in my App?

I have a Vertical linear layout with 2 item. One is a is a customview which is extended from a framelayout and the 2nd one is a textview with a drawable as background. The visibility have to be controlled dynamically from gone to visible.
The issue is that when i change the visibility of the item from gone to visible the order is not coming as i intended. The the second item is below the customview. I want it to come as the 2nd item, below the customview
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:textureview="http://schemas.android.com/apk/res-auto">
<LinearLayout
android:id="#+id/comment_holder"
android:orientation="vertical"
android:gravity="center_horizontal"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
<com.custom_views.CircularFrameLayout
android:id="#+id/comment_holder_circular_layout"
android:layout_gravity="center_horizontal"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
<ImageView
android:id="#+id/user_avatar"
android:visibility="gone"
android:layout_gravity="center_horizontal"
android:layout_width="#dimen/comment_avatar_width"
android:layout_height="#dimen/comment_avatar_width" />
<com.custom_views.PlaybackTextureView
android:visibility="gone"
android:id="#+id/playback_texture_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
textureview:isAuthorMode="true"/>
</com.custom_views.CircularFrameLayout>
<LinearLayout
android:visibility="gone"
android:id="#+id/c_holder"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:paddingTop="8dp"
android:paddingBottom="16dp"
android:paddingStart="4dp"
android:paddingEnd="4dp"
android:background="#drawable/chat_bubble_top_arrow_orange"
android:orientation="vertical">
<TextView
android:id="#+id/video_comment_user_name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="12sp"
android:textColor="#color/black_50"
android:fontFamily="sans-serif" />
</LinearLayout>
</LinearLayout>
</FrameLayout>
NOTE: I tried adding weight to the custom layout as 1. But it still didnt help.

set width and height as percentage in relative layout

I would like to have this: a ViewPager overlaid by 2 arrows
And I get what I want by this code. However, I got these warnings of lint :
this layout is useless (for dummy layouts)
nested weights are bad for performance.
I wonder if there is a better way to get this UI as I want.
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<android.support.v4.view.ViewPager
android:id="#+id/dialog_instruction_pager"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
</android.support.v4.view.ViewPager>
<!-- this LinearLayout overlays the ViewPager -->
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:orientation="vertical" >
<!-- This is just the container for the left and right arrows , it is allocated with only 20% of screen height-->
<LinearLayout
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight=".2"
android:orientation="horizontal" >
<!-- I want to align this to the left and set width only 5% of the parent -->
<ImageButton
android:id="#+id/instruction_dialog_left_arrow"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight=".05"
android:background="?android:attr/selectableItemBackground"
android:scaleType="fitCenter"
android:src="#drawable/arrow_left_grey" />
<!-- This is the dummy layout, standing in the middle of 2 arrows so they can be align to the left and right of the parent -->
<LinearLayout
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight=".8" >
</LinearLayout>
<!-- I want to align this to the right and set width only 5% of the parent-->
<ImageButton
android:id="#+id/instruction_dialog_right_arrow"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight=".05"
android:background="?android:attr/selectableItemBackground"
android:scaleType="fitCenter"
android:src="#drawable/arrow_right_grey" />
</LinearLayout>
</LinearLayout>
P.S: Is there any layout that allows align children left, right, bottom (like RelativeLayout) and also allows set width, height as percentage (like "weight" attribute in LinearLayout)?
Thank you !

try this
to avoid this layout is useless (for dummy layouts) u should android:background="#android:color/transparent" and add dummy view in that linear layout because layout should not be empty.
to avoid nested weights are bad for performance add one child linear layout.
and read my comments in code
and added parent layout for imageview to make image vertically center
try this code
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.v4.view.ViewPager
android:id="#+id/dialog_instruction_pager"
android:layout_width="wrap_content"
android:layout_height="wrap_content"></android.support.v4.view.ViewPager>
<!-- this LinearLayout overlays the ViewPager -->
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:orientation="vertical">
<!-- This is just the container for the left and right arrows , it is allocated with only 20% of screen height-->
<LinearLayout
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight=".2"
android:orientation="horizontal">
<!--child layout to avoid nested weight with `waighSum` property-->
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal"
android:weightSum="100">
<LinearLayout
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="5"
android:gravity="center_vertical"
android:orientation="horizontal">
<!-- I want to align this to the left and set width only 5% of the parent -->
<ImageButton
android:id="#+id/instruction_dialog_left_arrow"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="?android:attr/selectableItemBackground"
android:scaleType="fitCenter"
android:src="#drawable/icon_clock" />
</LinearLayout>
<!-- This is the dummy layout, standing in the middle of 2 arrows so they can be align to the left and right of the parent -->
<LinearLayout
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="90"
android:background="#android:color/transparent">// this line also makes layout usefull
<!-- dummy view becouse layout should not be empty -->
<View
android:layout_width="match_parent"
android:layout_height="match_parent" />
</LinearLayout>
<LinearLayout
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="5"
android:gravity="center_vertical"
android:orientation="horizontal">
<!-- I want to align this to the right and set width only 5% of the parent-->
<ImageButton
android:id="#+id/instruction_dialog_right_arrow"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="?android:attr/selectableItemBackground"
android:scaleType="fitCenter"
android:src="#drawable/icon_clock" />
</LinearLayout>
</LinearLayout>
</LinearLayout>
</LinearLayout>
</FrameLayout>
hope it works for u

Google introduced new API called android.support.percent
1)PercentRelativeLayout
2)PercentFrameLayout
Add compile dependency like
compile 'com.android.support:percent:23.1.1'
You can specify dimension in percentage so get both benefit of RelativeLayout and percentage
<android.support.percent.PercentRelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
<TextView
app:layout_widthPercent="40%"
app:layout_heightPercent="40%"
app:layout_marginTopPercent="15%"
app:layout_marginLeftPercent="15%"/>
</android.support.percent.PercentRelativeLayout/>

Try the below code and see whether it works,
This code will get the layout what you have attached
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<android.support.v4.view.ViewPager
android:id="#+id/dialog_instruction_pager"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#color/theme_blue" >
</android.support.v4.view.ViewPager>
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_centerInParent="true"
android:background="#drawable/ic_launcher" />
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_centerInParent="true"
android:background="#drawable/ic_launcher" />
</RelativeLayout>

Try using RelativeLayout and then set the left image to alignParentLeft and the right image to alignParentRight

ScrollView going behind button in Android

Why is the scrollview going behind the button here? I want the scrollview to stretch in height depending on the device but cant get it to work as it always goes behind the button.
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/detail_view"
style="#style/DetailView">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:orientation="vertical" >
<TextView
style="#style/TextView"
android:id="#+id/textview_message_title"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center">
</TextView>
<TextView
style="#style/TextView"
android:id="#+id/textview_message_date"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center">
</TextView>
<ScrollView
android:id="#+id/scrollview_message_text"
android:layout_height="wrap_content"
android:paddingBottom="20dip"
android:layout_width="fill_parent">
<TextView
style="#style/TextView"
android:id="#+id/textview_message_text"
android:layout_width="fill_parent"
android:layout_height="wrap_content">
</TextView>
</ScrollView>
</LinearLayout>
<LinearLayout style="#style/DetailView.Buttons"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<Button
style="#style/Button"
android:layout_marginTop="5dip"
android:id="#+id/button_view_file"
android:text="#string/viewfile"/>
</LinearLayout>
</RelativeLayout>

Here is a working copy of what I think you are looking for
1: Moved the buttons to the top of the relative layout ( added an id )
android:layout_alignParentBottom="true"
<LinearLayout android:id="#+id/buttons"
android:layout_alignParentBottom="true"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<Button
android:layout_height="wrap_content"
android:layout_width="wrap_content"
android:layout_marginTop="5dip"
android:id="#+id/button_view_file"
android:text="Button"/>
</LinearLayout>
2: Add in the layout containing the scroll change the width and height to match parent
but ( CRITICAL ) add android:layout_above="#id/buttons"
<LinearLayout
android:layout_above="#id/buttons"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#android:color/darker_gray"
android:gravity="center"
android:orientation="vertical" >
So putting it all together:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_height="match_parent"
android:layout_width="match_parent"
android:id="#+id/detail_view"
>
<!-- Buttons at the top of layout but aligned to the bottom -->
<LinearLayout android:id="#+id/buttons"
android:layout_alignParentBottom="true"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<Button
android:layout_height="wrap_content"
android:layout_width="wrap_content"
android:layout_marginTop="5dip"
android:id="#+id/button_view_file"
android:text="Button"/>
</LinearLayout>
<!-- Linear layout to fill screen, but assigned to layout above the buttons -->
<LinearLayout
android:layout_above="#id/buttons"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#android:color/darker_gray"
android:gravity="center"
android:orientation="vertical" >
<TextView
android:id="#+id/textview_message_title"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center">
</TextView>
<TextView
android:id="#+id/textview_message_date"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center">
</TextView>
<ScrollView
android:id="#+id/scrollview_message_text"
android:layout_height="wrap_content"
android:paddingBottom="20dip"
android:layout_width="fill_parent">
<TextView
android:id="#+id/textview_message_text"
android:layout_width="fill_parent"
android:layout_height="wrap_content">
</TextView>
</ScrollView>
</LinearLayout>
</RelativeLayout>
I removed the styles so I could see it in the layout an make sure this worked before posting. Hope this helps.
Relative layout allows you to layer elements on top of each other. So if that is not what you are looking for you need to make use of the toLeft, toRight, above, below directives to nudge the layouts into the correct position.

This happens because you use Relative layout as the root layout. So both layout are placed on the same place but the button layout is declared after the scrollview so it is shown above the scrollview
The opposite would happen if you were defining the button before the scrollview
So you should define it as shown below to achieve what you want.
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/detail_view"
style="#style/DetailView">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:layout_above="#id/layout_bottom"
android:orientation="vertical" >
<TextView
style="#style/TextView"
android:id="#+id/textview_message_title"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center">
</TextView>
<TextView
style="#style/TextView"
android:id="#+id/textview_message_date"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center">
</TextView>
<ScrollView
android:id="#+id/scrollview_message_text"
android:layout_height="wrap_content"
android:paddingBottom="20dip"
android:layout_width="fill_parent">
<TextView
style="#style/TextView"
android:id="#+id/textview_message_text"
android:layout_width="fill_parent"
android:layout_height="wrap_content">
</TextView>
</ScrollView>
</LinearLayout>
<LinearLayout
android:id="#+id/layout_bottom"
style="#style/DetailView.Buttons"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<Button
style="#style/Button"
android:layout_marginTop="5dip"
android:id="#+id/button_view_file"
android:text="#string/viewfile"/>
</LinearLayout>
</RelativeLayout>
or you can try and use LinearLayout as the root view and set
layout_height = "0dp"
layout_weight = "1"
to the layout containing the scrollview
using both these way will make the button stick to the bottom of the layout and the top layout will get all the remaining height.
Good Luck

Why is the scrollview going behind the button here?
Because it is coming first in your layout, ReletiveLayout and FrameLayout can be used to provide Z-ordering, So every child which comes later in your layout having higher z value so it goes up.Add android:layout_below = "#id/scrollview_message_text" to your last linearlayout or order your views within in mind of this characteristic of reletivelayout.

Unable to make all UI components appear in RelativeLayout

I want a RelativeLayout based android UI that looks like the below mock graphic:
Below is my layout xml:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/RelativeLayoutForPreview"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<!-- surface view that contains camera preview , and seats above #+id/linearLayoutToolbar -->
<SurfaceView
android:id="#+id/surfaceViewBarcodeScanner"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
<!-- LinearLayout that contains toolbar that is divided into 3 sections horizontally -->
<LinearLayout
android:id="#+id/linearLayoutToolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_below="#+id/surfaceViewBarcodeScanner"
android:orientation="horizontal" >
<ImageView
android:id="#+id/imageView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="#drawable/scanner_bottom_left" />
<ImageView
android:id="#+id/imageView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="#drawable/scanner_bottom_center_toolbar" />
<ImageView
android:id="#+id/imageView3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="#drawable/scanner_bottom_right_landscape_button" />
</LinearLayout>
</RelativeLayout>
I used Eclipse GUI palette and my own editing , however the output was not what I expected, the SurfaceView seems to covering all the screen, the LinearLayout at the bottom does not appear.
Snapshot of my current result on Galaxy S3 device:
Any help will be appreciated, Thanks.

Could you please try out to modify your layout as the follows:
Define your SurfaceView and set it's layout_above value to the ID of the linear layout made in the previous step. Set the layout_alignParentTop to true.
Define your bottom linear layout and set the layout_alignParentBottom to true.
Smart code snippet with only the important parts:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android">
<SurfaceView
android:id="#+id/surfaceViewBarcodeScanner"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_above="#+id/linearLayoutToolbar" />
<LinearLayout
android:id="#+id/linearLayoutToolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true" />
</RelativeLayout>
I hope this will solve your problem.

you can use Linearlayout instead of Realtive Layout
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<SurfaceView
android:id="#+id/surfaceViewBarcodeScanner"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_weight="1" />
<LinearLayout
android:id="#+id/linearLayoutToolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
>
<!-- inside elements -->
</LinearLayout>
</LinearLayout>
else you should use android:layout_above="#+id/linearLayoutToolbar" to your surfaceview
and remove android:layout_below attribute and add android:layout_alignParentBottom="true" to your toolbar view.

// try this
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/LinearLayoutForPreview"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="5dp"
android:orientation="vertical">
<LinearLayout
android:layout_height="0dp"
android:layout_weight="1"
android:layout_width="match_parent">
<SurfaceView
android:id="#+id/surfaceViewBarcodeScanner"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</LinearLayout>
<LinearLayout
android:id="#+id/linearLayoutToolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal" >
<LinearLayout
android:layout_height="wrap_content"
android:layout_width="0dp"
android:gravity="center"
android:layout_weight="1">
<ImageView
android:id="#+id/imageView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="#drawable/scanner_bottom_left" />
</LinearLayout>
<LinearLayout
android:layout_height="wrap_content"
android:layout_width="0dp"
android:gravity="center"
android:layout_weight="2">
<ImageView
android:id="#+id/imageView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="#drawable/scanner_bottom_center_toolbar" />
</LinearLayout>
<LinearLayout
android:layout_height="wrap_content"
android:layout_width="0dp"
android:gravity="center"
android:layout_weight="1">
<ImageView
android:id="#+id/imageView3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="#drawable/scanner_bottom_right_landscape_button" />
</LinearLayout>
</LinearLayout>
</LinearLayout>